Here's why:
* Zodiac signs are based on astrology, not astronomy. Astrological signs are based on the position of the Sun in the sky at the time of your birth. They are not determined by the constellations.
* The constellations and the zodiac signs do not align perfectly. The zodiac is divided into 12 sections, each corresponding to a specific constellation. However, due to the Earth's precession (a slow wobble), the constellations have shifted over time, meaning that the Sun is not always in the same constellation during the same time of year.
* The idea of Ophiuchus being a new zodiac sign is a hoax. It was popularized by a 2011 article on the website of the Minnesota Planetarium, which explained the discrepancy between the constellations and the zodiac but did not actually claim to be changing the zodiac.
So, your star sign hasn't changed. It's still the same as it always was, based on the traditional 12 signs of the zodiac.